Memory is a cornerstone ability upon which we build knowledge of ourselves and the world around us. Failures in memory, no matter how small, can significantly impact life success and mental health (including anxiety and depression). In adults, recognition memory is subserved by two processes, recollection and familiarity, which rely on partially distinct brain circuitry in the medial temporal lobe (MTL) and prefrontal cortex (PFC). Familiarity is the process that allows for the global assessment of memory strength. Recollection is the process that allows for the retrieval of distinct features associated with the context of the event. Recollection preferentially involves the hippocampus, a MTL structure characterized by its protracted developmental course. Neuroanatomical data illustrates that structural development of the hippocampus continues at least through the 5th year postnatally, which has been theoretically linked to functional changes observed in behavioral memory performance (e.g., improvements in autobiographical memory and episodic memory that occur during early childhood). However, this link has not yet been examined empirically. Thus, despite all we know about memory processes and associated neural circuitry in adults, the systematic study of its functional maturation early in life is notably absent. What remains relatively unexplored are age-related changes in the basic processes that underlie memory improvement in early childhood. This poses not only a gap in scientific understanding but also a barrier to development of intervention techniques that would facilitate or improve memory, particularly in those at-risk for impairment. Our goal is to elucidate mechanisms of change in memory development by systematically investigating changes in memory behavior and neural activity. Towards this end, the proposed research seeks to indentify windows during which memory processes develop that are informed by neurodevelopment. Specifically, we will examine familiarity and recollection processes during a memory retrieval task using a unique combination of electrophysiological and behavioral measures in early childhood. We hypothesize that electrophysiological and behavioral correlates of recollection (which rely on the hippocampus) will show substantial developmental change from 3 to 5 years of age, compared to changes in familiarity processes. Systematic study of memory development in humans has important implications for understanding memory in general and will ultimately further our understanding of disorders of memory (e.g., developmental amnesia), populations where memory is affected (e.g., individuals with depression), and disorders in which abnormalities of memory circuitry have been reported (e.g., depression, autism, and schizophrenia). PUBLIC HEALTH RELEVANCE: Memory impairment has been linked to learning disabilities in childhood and mental health disorders such as depression and schizophrenia in adolescence and adulthood. Our research aims to characterize the functional development of memory circuitry in the medial temporal lobe (MTL) by using event-related potentials to identify hippocampally-mediated recollective processes in early childhood and examine their development during a window of significant structural brain development. Knowledge gained from the outcomes of the proposed research will allow for the development of targeted prevention strategies for populations at-risk for memory impairment and those diagnosed with neurodevelopmental disorders known to affect MTL circuitry.